Method for reducing noise emissions on ground freezing construction sites

ABSTRACT

The invention relates to a method for producing a contiguous frozen mass in an area of ground wherein at least one first cooling lance is introduced into the area of ground in which the contiguous frozen mass is to be generated, wherein a first fluid coolant is fed into the at least first cooling lance to support the formation of a contiguous frozen mass which surrounds the at least first cooling lance, the first coolant evaporates during formation of the contiguous frozen mass and the evaporated coolant is displaced out of the at least first cooling lance into a means for holding and/or dissipating the evaporated coolant. In this context, it is provided according to the invention that noise emissions generated during the creation of the contiguous frozen mass are minimised by a soundproofing means. The invention relates further to a device for performing the method according to the invention.

The invention relates to a method for producing a contiguous frozen mass in an area of ground more quietly and a device for carrying out the method.

Freezing methods are used most often to solidify or waterproof building land. Methods are known in which liquid nitrogen or liquefied air are used as coolant. It is also known to freeze the ground with a brine the temperature of which is itself controlled with a refrigeration system. Icing with nitrogen takes place considerably more quickly than with brine, due to the low temperature of liquid nitrogen, but on the other hand the running costs (energy costs) for longer freezing times are significantly higher with liquid nitrogen than with brine. The requirements regarding freezing durations (constantly shorter) and maintaining (constantly longer) have resulted in the implementation of different ground icing methods, in which the frozen mass was first built using liquid nitrogen and maintenance of this frozen mass was subsequently assured using brine.

As a result of the increasing trend towards urbanization and in order to comply with the accompanying, progressively stricter regulations and noise control provisions, it is necessary to implement noise protection measures that will significantly reduce noise emissions, most importantly at aboveground ground freezing construction sites. The development of a soundproofing system enables the ground freezing method using liquid nitrogen to be implemented even with stringent noise protection requirements in place.

In this context, it is the object of the present invention to provide a method installing the ground freezing equipment under optimum noise protection conditions which also enables use of ground freezing methods in densely populated regions with strict noise protection provisions.

This object is solved with a method having the features of claim 1 and a device having the features of claim 8.

Accordingly, the method according to the invention for creating a contiguous frozen mass in an area of ground provides that at least one first cooling lance is introduced into the area of ground in which the contiguous frozen mass is to be created, wherein a first fluid coolant is fed into the at least first cooling lance to support the formation of a contiguous frozen mass which surrounds the at least first cooling lance, the first coolant evaporates during formation of the contiguous frozen mass and the evaporated coolant is displaced out of the at least first cooling lance into a means for holding and/or dissipating the evaporated coolant, particularly an exhaust manifold or an outlet pipe.

According to the invention it is provided that noise emissions generated during the creation of the contiguous frozen mass are minimised by a soundproofing means.

For the purposes of the invention, a soundproofing means is particularly understood to mean a device or method which reduces noise emissions. Non-limiting examples of such noise minimising devices include a noise damping material, a silencer or an acoustic insulation tube. Non-limiting examples of noise minimising methods include a method for generating counter-noise or active noise control.

The first fluid coolant is in particular a liquefied gas or gas mixture, preferably liquid nitrogen or liquefied air.

The exhaust manifold is in particular a pipe section to which multiple cooling lances can be connected for the purpose of dissipating the gas-phase coolant.

In one embodiment of the method according to the invention, it is provided that the soundproofing means is embodied as a silencer in the at least first cooling lance.

Such a silencer may be a reflective silencer, in which sound is reflected by baffle walls, cross-sectional expansions and/or cross-sectional constrictions, so that the amplitude of the sound pressure is averaged. Alternatively, the silencer may also be an absorptive silencer, in which the sound energy is at least partially absorbed by materials that absorb sound, for example porous materials such as rock wool, glass wool or glass fibers, and converted into heat.

In a further embodiment of the method according to the invention, it is provided that the silencer in the at least first cooling lance is embodied as a pipe section lined with a sound insulating material.

In a further embodiment of the method according to the invention, it is provided that the silencer in the at least first cooling lance is embodied as a shroud made from a sound insulating material which surrounds the at least first cooling lance.

In a further embodiment of the method according to the invention, it is provided that the soundproofing means is embodied as silencers in the medium for containing and/or dissipating the evaporated coolant.

In a further embodiment of the method according to the invention, it is provided that the soundproofing means is embodied as silencers in the exhaust manifold.

In a further embodiment of the method according to the invention, it is provided that the silencers in the exhaust manifold are embodied as installations in the exhaust manifold which can reduce the flow boundaries.

In a further embodiment of the method according to the invention, it is provided that the soundproofing means is embodied as silencers in the outlet pipe, wherein particularly the outlet pipe is lined with or wrapped in an sound insulating material.

In a further embodiment of the method according to the invention, it is provided that the at least first cooling lance is connected to a coolant reservoir via a first connection, and the soundproofing means is embodied as silencers or an acoustic insulation tube in the first connection.

In particular, the coolant reservoir is a tank or receptacle.

In a further embodiment of the method according to the invention, it is provided that the exhaust manifold or the outlet pipe is connected to the cooling lance via a second connection, and the soundproofing means is embodied as silencers or an acoustic insulation tube in the second connection.

In particular such an acoustic insulation tube is a tube of which the inside is lined with a sound insulating or sound absorbing material. An acoustic insulation tube may also be a corrugated tube with inliner, e.g., a mesh which is placed over the internal corrugations in the tube to reduce the turbulences in the flow.

The first connection and/or the second connection is in particular a duct, preferably a pipeline or a corrugated tube.

The acoustic insulation tube may be arranged for example inside the first connection and/or the second connection, preferably a pipeline, and the first coolant flows through said tube. Alternatively, the duct may be surrounded or encased by an acoustic insulation tube or a sound damping or sound insulating material.

In a further embodiment of the method according to the invention, it is provided that the soundproofing means comprises a containment installation which encloses at least the exhaust manifold, the outlet pipe, the first connection, the second connection and/or the aboveground area of the ground in which the at least first cooling lance is introduced into the ground, and the soundproofing means further comprises at least one amplifier which is designed to minimise the noise emissions generated with counter-noise and/or active noise control.

The containment installation may be a curtain.

Alternatively, the containment installation may include rigid elements. The at least one amplifier is preferably mounted in one of the rigid elements.

In a further embodiment of the method according to the invention, it is provided that the soundproofing means further comprises at least one microphone. The microphone is preferably mounted in one of the rigid elements of the containment installation.

According to a further aspect of the invention, a device is provided for creating a contiguous frozen mass in an area of ground. The device comprises:

-   -   at least a first cooling lance, which is designed to introduce a         fluid coolant into an area of ground,     -   a coolant reservoir, which is designed to supply the fluid         coolant, and     -   a means for containing and/or dissipating an evaporated coolant,         particularly an exhaust manifold, which is designed to         accommodate an evaporated coolant, or an outlet pipe for leading         the evaporated coolant away.

According to the invention it is provided that the device further includes a soundproofing means which is designed to minimise noise emissions that are generated during creation of the contiguous frozen mass.

In particular, the device according to the invention is suitable and designed for carrying out the method according to the invention.

In one embodiment of the device according to the invention, it is provided that the soundproofing means is embodied as silencers in the at least first cooling lance.

In a further embodiment of the device according to the invention, it is provided that the soundproofing means is embodied as silencers in the exhaust manifold.

In a further embodiment of the device according to the invention, it is provided that the soundproofing means is embodied as silencers in the outlet pipe.

In a further embodiment of the device according to the invention, it is provided that the at least first cooling lance is connected to a coolant reservoir via a first connection, and the soundproofing means is embodied as silencers or an acoustic insulation tube in the first connection, wherein the first connection is designed in particular as a duct, preferably a pipeline or corrugated tube.

In a further embodiment of the device according to the invention, it is provided that the exhaust manifold or the outlet pipe is connected to the at least first cooling lance via a second connection, and the soundproofing means is embodied as silencers or an acoustic insulation tube in the second connection, wherein the second connection is embodied in particular as a duct, preferably as a pipeline or corrugated tube.

In a further embodiment of the device according to the invention, it is provided that the device comprises a containment installation as soundproofing means, which encloses at least the exhaust manifold, the outlet pipe, the first connection, the second connection and/or the aboveground portion of the area of ground into which the at least first cooling lance is inserted, and the device further comprises at least one amplifier as soundproofing means which is designed to minimise the noise emissions generated with counter-noise.

BRIEF DESCRIPTION OF THE DRAWINGS

In a further embodiment of the device according to the invention, it is provided that the device further comprises at least one microphone.

Further features and advantages of the invention will be explained in the following descriptions of a drawing of embodiments of the invention with reference to the figures. In the drawing:

FIG. 1 is a schematic representation of a system for carrying out the method according to the invention;

FIG. 2 is a schematic representation of another system for carrying out the method according to the invention.

EXAMPLES

The present invention relates in particular to a method for reducing noise emissions on ground freezing construction sites.

During installation of the freezing lances and the hardware, noise protection measures are to be adopted

-   -   which can be installed directly in the freezing lance         (silencers),     -   which can be installed in the connection duct between the         freezing lance and the exhaust manifold (silencers and acoustic         insulation tubes),     -   which can be installed in the exhaust manifold (silencers)     -   which can be installed in the exhaust duct (outlet pipe)         (silencers and acoustic insulation tubes), and/or     -   which have the effect of reducing overall noise by active noise         reduction with counter-noise measures. In the case of active         noise reduction with counter-noise measures the installation         must be enclosed, which may be assured with rigid elements or by         a curtain, for example. Microphones and amplifiers are installed         in these elements and serve to reduce the incoming background         noise through counter-noise.

FIG. 1 shows a schematic representation of an embodiment of the installation according to the invention or the method according to the invention for creating a connected frozen or iced mass 1.

In this context, the first cooling lance 10 is introduced into the area of ground 100. The cooling lance 10 may be introduced into the area of ground 100 either vertically or horizontally. In a freezing phase, during which the contiguous frozen mass 1 is created in the area of ground 100, a first coolant T in the form of liquid nitrogen is fed into the corresponding cooling lance 10. Later, after the frozen mass 1 has been created, the flow of the first coolant T may be throttled or stopped completely.

The first coolant T (liquid nitrogen) is preferably fed into the inner pipe from a liquid nitrogen tank 20 via a pipeline 21, then exits the respective opening 12 which is positioned opposite the frontal face 14 of the outer pipe 13 and flows back in the respective outer pipe 13. In this process, the first coolant T is evaporated while cooling the area of ground 1, wherein gas phase exits the outer pipe 13 of the first cooling lance 10 and is immediately directed into an exhaust manifold 22 via a further pipeline 23, and from there may optionally be discharged to a gas outlet pipe 24.

In order to reduce the noise emissions generated during the creation of the contiguous frozen mass 1, it is provided according to the invention to implement one or more soundproofing means. In this connection, the system represented in FIG. 1 includes a silencer 30 in the first cooling lance, a silencer 31 in the exhaust manifold 22, a silencer 37 in the gas outlet pipe 24, and silencers 32, 33 or acoustic insulation tubes in the pipelines 21, 23.

The system represented in FIG. 2 includes a containment installation 34 as an additional noise insulation element, inside of which at least one amplifier 35 is arranged for generating counter-noise and at least one microphone 36. The containment installation 34 encloses the exhaust manifold 22, the gas outlet pipe 24, the pipelines 21, 23 that connect the liquid nitrogen tank 20 to the cooling lance 10 and the cooling lance 10 to the exhaust manifold 22, and the aboveground region of the area of ground 100, in which the contiguous frozen mass 1 is to be created, but not the liquid nitrogen tank 20. In this context, the microphone 36 is provided to measure the noise emissions that are to be suppressed. This way, it is possible to determine the level of counter-noise that is required to generate a destructive interference and minimise the noise emissions. The containment installation 34 may be a curtain or a plurality of rigid elements, wherein in the latter case the amplifier 35 and the microphone 36 are preferably installed in at least one of the rigid elements of the containment installation 34.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

The entire disclosures of all applications, patents and publications, cited herein and of corresponding German application No. 10 2018 002 821.7, filed Apr. 6, 2018, are incorporated by reference herein.

The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

LIST OF REFERENCE SIGNS

-   1 Frozen mass -   10 First cooling lance -   11 Inner pipe -   12 Opening -   13 Outer pipe -   14 Frontal face -   20 Liquid nitrogen tank -   21 Connection duct from liquid nitrogen tank to cooling lance -   22 Exhaust manifold -   23 Connection duct from cooling lance to exhaust manifold -   24 Gas outlet pipe -   30 Silencer, cooling lance -   31 Silencer, exhaust manifold -   32 Silencer/Acoustic insulation tube -   33 Silencer/Acoustic insulation tube -   34 Containment installation -   35 Amplifier for counter-noise -   36 Microphone -   37 Silencer, gas outlet pipe -   100 Area of ground -   T First fluid coolant (cold) -   T′ First gas-phase coolant (warm) 

1. Method for creating a contiguous frozen mass (1) in an area of ground (100), wherein at least one first cooling lance (10) is introduced into the area of ground (100) in which the contiguous frozen mass (1) is to be created, a first fluid coolant (T) is fed into the at least first cooling lance (10) to support the formation of a contiguous frozen mass (1) which surrounds the at least first cooling lance (10), the first coolant (T) evaporates during formation of the contiguous frozen mass (1) and the evaporated coolant (T′) is led out of the at least first cooling lance (10) in into a means (22, 24) for accommodating and/or dissipating the evaporated coolant (T′), particularly an exhaust manifold (22) and/or an outlet pipe (24), characterized in that noise emissions generated during the creation of the contiguous frozen mass (1) are minimised by a soundproofing means (30, 31, 32, 33, 34, 35, 36, 37).
 2. Method according to claim 1, characterized in that the soundproofing means is embodied as silencers (30) in the at least first cooling lance (10).
 3. Method according to claim 1, characterized in that the soundproofing means is embodied as silencers (31, 37) in the exhaust manifold (22) and/or in the outlet pipe (24).
 4. Method according to claim 1, characterized in that the at least first cooling lance (10) is connected to a coolant reservoir (20) via a first connection (21), and the soundproofing means is embodied as silencers (32) or an acoustic insulation tube (32) in the first connection (21).
 5. Method according to claim 1, characterized in that the exhaust manifold (22) or the outlet pipe (24) is connected to the at least first cooling lance (10) via a second connection (23), and the soundproofing means is embodied as silencers (33) or an acoustic insulation tube (33) in the second connection (23).
 6. Method according to claim 1, characterized in that the soundproofing comprises a containment installation (34) which encloses at least the exhaust manifold (22), the outlet pipe (24), the first connection (21), the second connection (23) and/or the aboveground region of the area of ground (100) into which the at least first cooling lance (10) is introduced, and the soundproofing means further comprises at least one amplifier (35) which is designed to minimise the noise emissions generated by counter-noise.
 7. Method according to claim 6, characterized in that the soundproofing means further comprises at least one microphone (36).
 8. Device for creating a contiguous frozen mass in an area of ground, including at least a first cooling lance (10), which is designed to introduce a fluid coolant (T) into an area of ground (100), a coolant reservoir (20), which is designed to supply the fluid coolant (T), and a means for accommodating and/or dissipating an evaporated coolant (T′), particularly an exhaust manifold (22), which is designed to accommodate the evaporated coolant (T′), or an outlet pipe (24) for leading the evaporated coolant (T′) away, characterized in that the device further includes a soundproofing means (30, 31, 32, 33, 34, 35, 36, 37) which is designed to minimise the noise emissions that are generated during creation of the contiguous frozen mass (1).
 9. Device according to claim 8, characterized in that the soundproofing means is embodied as silencers (30) in the at least first cooling lance (10).
 10. Device according to claim 8, characterized in that the soundproofing means is embodied as silencers (31, 37) in the exhaust manifold (22) or in the outlet pipe (24).
 11. Device according to claim 8, characterized in that the at least first cooling lance (10) is connected to the coolant reservoir (20) via a first connection (21), and the soundproofing means is embodied as silencers (32) or an acoustic insulation tube (32) in the first connection (21).
 12. Device according to claim 8, characterized in that the exhaust manifold (22) or the outlet pipe (24) is connected to the at least first cooling lance (10) via a second connection (23), and the soundproofing means is embodied as silencer (33) or an acoustic insulation tube (33) in the second Connection (23).
 13. Device according to claim 8, characterized in that the device comprises a containment installation (34) as soundproofing means, which encloses at least the exhaust manifold (22), the outlet pipe (24), the first connection (21), the second connection (23) and/or the aboveground region of the area of ground (100) into which the at least first cooling lance (10) is introduced, and the device further comprises at least one amplifier (35) as soundproofing means which is designed to minimise the noise emissions generated with counter-noise.
 14. Device according to claim 13, characterized in that the device further comprises at least one microphone (36). 